Microembolic signals predict cerebral ischaemic events in patients with moyamoya disease

Development and External Validation of Nomogram for Cerebral Infarction in Moyamoya Diseases

More than 60% of moyamoya disease (MMD) patients suffers cerebral ischemia and preoperative cerebral infarction (CI) increases the risk of postoperative stroke and unfavorable outcome. We established a nomogram system for risk stratification of CI to help tailoring individualized management. We enrolled 380 patients including 680 hemispheres for the training cohort from our hospital and 183 patients including 348 hemispheres for the validation cohort from multicenter. A nomogram for CI was formulated based on the multivariable logistic regression analysis. The predictive accuracy and discriminative ability of nomogram were determined with concordance index (C-index) and calibration curve. For the training cohort, 246 hemispheres (36.2%) were found with CI. In multivariable logistic regression used generalized estimating equations approach, anterior choroidal artery (AchA) grade (grade 1, OR 0.214, 95%CI 0.124-0.372, P < 0.001; grade 2, OR 0.132, 95%CI 0.066-0.265, P < 0.001), cerebral perfusion (OR 4.796, 95%CI 2.922-7.872; P < 0.001), white matter hyperintensity (OR 3.652, 95%CI 1.933-6.902; P < 0.001), brush sign (OR 3.555, 95%CI 2.282-5.538; P < 0.001), and ivy sign (equivocal, OR 4.752, 95%CI 2.788-8.099, P < 0.001; present, OR 8.940, 95%CI 4.942-16.173, P < 0.001) were significant factors for CI. The C-index of the nomogram for predicting cerebral infarction was 0.890 (95%CI 0.866-0.915) in the training cohort and 0.847 (95%CI 0.805-0.889) in the validation cohort. The nomogram composed of AchA grade, cerebral perfusion, white matter hyperintensity, brush sign, and ivy sign could provide risk stratification of CI before surgery in patients with MMD. Active treatment might be recommended before CI, which could reduce the risk of stroke after surgery.

Chinese expert consensus on the treatment of MMD

Moyamoya disease (MMD), also known as spontaneous occlusion of the circle of Willis, is defined by progressive stenosis or occlusion of the internal carotid arteries, and it can progress to the anterior, middle, and posterior cerebral arteries. As these arteries are gradually stenosed, a collateral network of capillaries develops at the base of the brain, producing the characteristic reticulate appearance ("puff of smoke") on angiography. Therefore, it was named by Suzuki and Takaku in 1969 after the Japanese term "moyamoya" (Suzuki and Takaku, Arch Neurol 20:288-299, 1969). MMD is most common in East Asian countries such as Japan and Korea, and it shows a slight female predominance. MMD is mainly characterized by ischemia and hemorrhage. Hemorrhagic MMD is very rare in children, and most cases occur in adults due to the rupture of the compensatory blood vessels, which often leads to hemorrhagic symptoms (Scott and Smith, N Engl J Med 360:1226-1237, 2009). In recent years, the diagnosis rate has increased with the popularization of imaging techniques. However, the pathogenesis of MMD is still not completely understood, and there is currently no evidence to suggest that drug treatment can delay or even reverse the progression of MMD. The current drug treatment for in MMD only targets its clinical symptoms, including ischemia and hemorrhage. The main choice of treatment for MMD is surgical revascularization. As an increasing number of hospitals have developed surgical treatment for MMD, our compiling group has jointly discussed the formulation of a consensus among Chinese experts on the treatment of MMD.

European Stroke Organisation (ESO) Guidelines on Moyamoya angiopathy: Endorsed by Vascular European Reference Network (VASCERN)

The European Stroke Organisation (ESO) guidelines on Moyamoya Angiopathy (MMA), developed according to ESO standard operating procedure and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology, were compiled to assist clinicians in managing patients with MMA in their decision making. A working group involving neurologists, neurosurgeons, a geneticist and methodologists identified nine relevant clinical questions, performed systematic literature reviews and, whenever possible, meta-analyses. Quality assessment of the available evidence was made with specific recommendations. In the absence of sufficient evidence to provide recommendations, Expert Consensus Statements were formulated. Based on low quality evidence from one RCT, we recommend direct bypass surgery in adult patients with haemorrhagic presentation. For ischaemic adult patients and children, we suggest revascularization surgery using direct or combined technique rather than indirect, in the presence of haemodynamic impairment and with an interval of 6–12 weeks between the last cerebrovascular event and surgery. In the absence of robust trial, an Expert Consensus was reached recommending long-term antiplatelet therapy in non-haemorrhagic MMA, as it may reduce risk of embolic stroke. We also agreed on the utility of performing pre- and post- operative haemodynamic and posterior cerebral artery assessment. There were insufficient data to recommend systematic variant screening of RNF213 p.R4810K. Additionally, we suggest that long-term MMA neuroimaging follow up may guide therapeutic decision making by assessing the disease progression. We believe that this guideline, which is the first comprehensive European guideline on MMA management using GRADE methods will assist clinicians to choose the most effective management strategy for MMA.

Microembolic signals and antiplatelet therapy in Moyamoya angiopathy

BACKGROUND

Embolism as a cause of stroke is widely neglected in Moyamoya angiopathy (MMA), and recommendations for use of antiplatelet therapy (APT) vary. We examined the presence of microembolic signals (MES) during transcranial Doppler (TCD) monitoring and assessed the effects of APT on the occurrence of MES in MMA.

PATIENTS AND METHODS

We retrospectively analysed patients with MMA treated at our centre between 2011 and 2021. TCD was performed at first presentation and at most visits, while number of visits varied between individual patients. TCD was performed for 30 min bilaterally. Patient demographics, vascular risk factors, and antiplatelet treatment were collected from each clinic visit and ischemic and haemorrhagic episodes were captured as recorded during follow-up visits.

RESULTS

209 patients were included in the analysis (mean age 38.7 ± 15.3, 28% male). 21 patients with 27 MES-positive TCD examinations were identified (10%). Patient characteristics were similar in MES-positive and MES-negative groups. However, recent ischemic events were detected at a significantly higher rate in MES-positive patients (42.9% vs 4.8%, p < 0.001). After MES detection, change of antiplatelet drug regime was performed, leading to loss of MES in all cases. Dual APT was preferably used in the MES-positive group (p < 0.001) but no significant difference of haemorrhage during follow-up-visits was observed. Reduction of APT before bypass-surgery triggered MES in four patients.

CONCLUSION

APT is required in patients with MMA. MES monitoring may help to identify risk patients in need of intensified APT.

Is patent foramen ovale the cause of stroke in a patient with moyamoya disease?

We reported a case of ischaemic stroke with moyamoya disease with simultaneous occurrence of patent foramen ovale. The patient underwent percutaneous closure of patent foramen ovale and was scheduled for follow-up.

Infarction Patterns and Recurrent Adverse Cerebrovascular Events in Moyamoya Disease

For moyamoya disease (MMD) patients who suffered an acute ischemic attack, the infarction patterns on DWI and its association with recurrent adverse cerebrovascular events (ACEs) after bypass surgery remain unknown. 327 patients who suffered an acute ischemic attack and received following revascularization surgery were retrospectively reviewed and were divided into three patterns according to the lesion number and distribution on DWI that obtained within 7 days of onset: no acute infarction (NAI), single acute infarction (SAI), and multiple acute infarctions (MAIs). We used Cox proportional hazard models to estimate hazard ratios (HR) for associations of infarction patterns and the risk of recurrent ACEs and strokes. Over a median follow-up of 41 months (IQR 26-60), there were 61 ACEs and 27 strokes. Compared to the NAI cohort, patients with SAI (HR, 2.92; 95% CI, 1.41-6.05; p = 0.004) and MAIs (HR, 4.44; 95% CI, 2.10-9.41; p < 0.001) were associated with higher risk of ACEs recurrences. In analysis adjusted for age and surgery modalities, the corresponding HR was 2.90 (95% CI: 1.41-5.98) for SAI and 4.10 (95% CI: 1.95-8.63) for MAIs, and this effect remained persistent on further adjustment for several potential confounders. Similar but less precise association was found in separate analysis that only takes into account stroke recurrences. Thus, different infarction patterns on DWI imply different risks of recurrent ACEs, and more attention should be paid to prevent ACEs in MMD patients with MAIs.

Imaging Pattern and the Mechanisms of Postoperative Infarction After Indirect Revascularization in Patients with Moyamoya Disease

OBJECTIVE

To develop preventive strategies against postoperative infarction after indirect revascularization surgery in patients with moyamoya disease (MMD), we evaluated clinical information, with a specific focus on the imaging pattern of postoperative infarction.

METHODS

We retrospectively evaluated 421 surgical procedures performed in 354 (262 pediatric and 159 adult) patients with MMD from April 1991 to March 2021 at our institute. In addition to clinical information, raw images of postoperative infarction were collected and categorized into subtypes by the location of the infarction.

RESULTS

Symptomatic and asymptomatic postoperative infarction occurred in 47 and 12 patients (11.1% and 2.6%), respectively, and more than half (51.7%) of these cases of postoperative infarction occurred immediately or the day after the surgery. Cortical infarction around the craniotomy site was the most frequent pattern observed (50/59, 84.8%), and some of these cases seemed to occur under local compression from epidural or subdural hematomas (15/50, 30.0%). Ipsilateral white matter infarctions located in the watershed area (9/59, 15.3%) and contralateral infarctions (3/59, 5.1%) were also observed. Four patients (1.0%) showed sudden occlusions of ipsilateral or contralateral large intracranial arteries immediately after surgery. Postoperative infarction caused permanent neurologic deficits in 7 patients (1.7%), and all included the cortex outside the craniotomy site.

CONCLUSIONS

Local cortical irritation, hemodynamic fluctuation, and thromboembolic events were suggested as possible mechanisms of postoperative infarction after indirect revascularization in patients with MMD. Minimizing cortical irritation, maintaining adequate cerebral blood flow, and perioperative antiplatelet agents might decrease the incidence of postoperative infarction.

Differences in Clinical Features among Different Onset Patterns in Moyamoya Disease

Moyamoya disease is characterized by severe stenosis at the ends of the bilateral internal carotid arteries and the development of collateral circulation. The disease is very diverse in terms of age at onset, onset patterns, radiological findings, and genetic phenotypes. The pattern of onset is mainly divided into ischemic and hemorrhagic onsets. Recently, the opportunity to identify asymptomatic moyamoya disease, which sometimes manifests as nonspecific symptoms such as headache and dizziness, through screening with magnetic resonance imaging has been increasing. Various recent reports have investigated the associations between the clinical features of different onset patterns of moyamoya disease and the corresponding imaging characteristics. In this article, we have reviewed the natural history, clinical features, and imaging features of each onset pattern of moyamoya disease.

Clinical Role of Microembolic Signals in Adult Moyamoya Disease With Ischemic Stroke

Background and Purpose- Hemodynamic compromise has been implicated in moyamoya disease (MMD) with transient ischemic attacks or ischemic stroke. However, increasing evidence supports the notion that artery-to-artery embolism may also contribute to ischemic events based on microembolic signal (MES) monitoring. Methods- A total of 48 patients aged between 20 and 60 years with newly diagnosed MMD were enrolled and angiographically classified according to the Suzuki staging system. For detection of MESs, transcranial Doppler was performed at the middle cerebral artery bilaterally for a 30-minute period. Mean flow velocities in the middle cerebral artery were also evaluated and categorized into low (<40 cm/s), normal (40-80 cm/s), and high (>80 cm/s). Clinical characteristics, cerebral angiography findings, recent ischemic events within 3 months, and antiplatelet medication were correlated with transcranial Doppler findings. Results- MESs were detected in 11 of the 48 patients (23%), with a frequency of 11 of 89 (12%) examined hemispheres. The mean number of MESs was 2 (range, 1-6). Six of the 11 hemispheres (55%) presented with ischemic strokes or transient ischemic attacks, and 2 (18%) presented with hemorrhagic strokes. The presence of MESs was associated with recent ischemic events ( P=0.024) and high mean flow velocities ( P=0.016), which was usually observed in Suzuki stage I and II (early-stage MMD). After controlling for age, sex, and antiplatelet medication, both recent ischemic events (odds ratio, 6.294; 95% CI, 1.345-29.457; P=0.019) and high mean flow velocities (odds ratio, 6.172; 95% CI, 1.235-31.25; P=0.027) were found to be independent predictors of MESs. Conclusions- MESs were observed in patients with high mean flow velocities, particularly early-stage MMD, and clinically associated with recent ischemic events. A randomized controlled study is necessary to determine the efficacy of antiplatelet agents in the treatment of MES-positive MMD.

Hemodynamics and oxygen extraction in chronic large artery steno-occlusive disease: Clinical applications for predicting stroke risk

Depending on the adequacy of collateral sources of blood flow, arterial stenosis or occlusion may lead to reduced perfusion pressure and ultimately reduced blood flow in the distal territory supplied by that vessel. There are two well-defined compensatory mechanisms to reduced pressure or flow - autoregulatory vasodilation and increased oxygen extraction fraction. Other changes, such as metabolic downregulation, are likely. The positive identification of autoregulatory vasodilation and increased oxygen extraction fraction in humans is an established risk factor for future ischemic stroke in some disease states such as atherosclerotic carotid stenosis and occlusion. The mechanisms by which ischemic stroke may occur are not clear, and may include an increased vulnerability to embolic events. The use of hemodynamic assessment to identify patients with occlusive vasculopathy at an increased risk for stroke is very appealing for several different patient populations, such as those with symptomatic intracranial atherosclerotic disease, moyamoya phenomenon, complete internal carotid artery occlusion, and asymptomatic cervical carotid artery stenosis. While there is very good data for stroke risk prediction in some of these groups, no intervention based on these tools has been proven effective yet. In this manuscript, we will review these topics above and identify areas for future research.

Direct Visualization of Arterial Emboli in Moyamoya Syndrome

BACKGROUND

Hemodynamic insufficiency is often considered the cause of ischemic stroke in patients with moyamoya syndrome. While high-intensity transient signals (HITS) on transcranial Doppler (TCD) have been reported in this population, the relationship between these signals and ischemic symptoms is not clearly established. Accordingly, current treatment is directed at improving perfusion.

CLINICAL PRESENTATION

We present two patients with symptoms of cerebral ischemia and angiographic findings of moyamoya syndrome. In each case, ischemia may have been caused by either hypoperfusion or embolization. Patient A presented with multifocal right middle cerebral artery (MCA) territory infarctions and angiographic findings consistent with moyamoya disease. She underwent right superficial temporal artery-MCA bypass. Intra-operatively, embolic material was observed and recorded traveling through the recipient MCA branch artery on two occasions. Postoperative TCD demonstrated HITS that resolved with uptitration of antiplatelet therapy. Patient B presented with multifocal, embolic-appearing left MCA infarctions, and unilateral angiographic moyamoya syndrome. She was found to have HITS in the left MCA, which eventually resolved with a combination of antiplatelets and anticoagulation.

CONCLUSION

Hemodynamic compromise may not be the only cause of brain infarction in patients with moyamoya syndrome. Observations from these two patients provide both direct visualization and TCD evidence of embolization as a potential etiology for brain ischemia. Future investigations into the role of antithrombotic agents should be considered.

Baseline Hemodynamic Impairment and Future Stroke Risk in Adult Idiopathic Moyamoya Phenomenon: Results of a Prospective Natural History Study

BACKGROUND AND PURPOSE

The purpose was to test the hypothesis that increased oxygen extraction fraction (OEF), a marker of severe hemodynamic impairment measured by positron emission tomography, is an independent risk factor for subsequent ischemic stroke in this population.

METHODS

Adults with idiopathic moyamoya phenomena were recruited between 2005 and 2012 for a prospective, multicenter, blindly adjudicated, longitudinal cohort study. Measurements of OEF were obtained on enrollment. Subjects were followed up for the occurrence of ipsilateral ischemic stroke at 6-month intervals. Patients were censored at the time of surgical revascularization or at last follow-up. The primary analysis was time to ischemic stroke in the territory of the occlusive vasculopathy.

RESULTS

Forty-nine subjects were followed up during a median of 3.7 years. One of 16 patients with increased OEF on enrollment had an ischemic stroke and another had an intraparenchymal hemorrhage. Three of 33 patients with normal OEF had an ischemic stroke. On a per-hemisphere basis, 21 of 79 hemispheres with moyamoya vasculopathy had increased OEF at baseline. No ischemic strokes and one hemorrhage occurred in a hemisphere with increased OEF (n=21). Sixteen patients (20 hemispheres), including 5 with increased OEF at enrollment, were censored at a mean of 5.3 months after enrollment for revascularization surgery.

CONCLUSIONS

The risk of new or recurrent stroke was lower than expected. The low event rate, low prevalence of increased OEF, and potential selection bias introduced by revascularization surgery limit strong conclusions about the association of increased OEF and future stroke risk.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00629915.

Infarct Pattern and Collateral Status in Adult Moyamoya Disease: A Multimodal Magnetic Resonance Imaging Study

BACKGROUND AND PURPOSE

Moyamoya disease (MMD) is a unique cerebrovascular disease characterized by the progressive stenosis of large intracranial arteries and a hazy network of basal collaterals, called moyamoya vessels. Although hemodynamic studies have been applied in MMD patients, the mechanisms of stroke in MMD are still unclear. The present study evaluated the infarct pattern and collateral status using multimodal magnetic resonance imaging in MMD patients.

METHODS

Adult MMD patients with acute ischemic stroke were prospectively recruited, and infarct pattern on diffusion-weighted imaging was evaluated. A collateral flow map, derived from magnetic resonance perfusion-weighted imaging data, was generated through automatic postprocessing, and collateral status was assigned into 3 grades. Transcranial Doppler monitoring was performed to detect microembolic signals in selected patients.

RESULTS

A total of 67 hemispheres (31 patients with bilateral and 5 patients with unilateral MMD) were analyzed. Most patients (83.7%) showed embolic pattern and rarely deep (9.3%) or hemodynamic infarct pattern (7.0%) on diffusion-weighted imaging. Most cases (86%) showed good collateral status, and few patients with acute infarcts of embolic pattern showed poor collateral status (n=7). One third (31.6%) of patients who underwent transcranial Doppler monitoring showed microembolic signals.

CONCLUSIONS

In the studied population of adult MMD patients, embolic phenomenon played an important role in ischemic stroke. Therapeutic strategies against thromboembolism, as well as collateral enhancing strategies targeting improvement of hemodynamic status or increased washout of emboli, are warranted.

Prehospital antiplatelet use and functional status on admission of patients with non-haemorrhagic moyamoya disease: a nationwide retrospective cohort study (J-ASPECT study)

OBJECTIVES

To elucidate the association between antiplatelet use in patients with non-haemorrhagic moyamoya disease before hospital admission and good functional status on admission in Japan.

DESIGN

Retrospective, multicentre, non-randomised, observational study.

SETTING

Nationwide registry data in Japan.

PARTICIPANTS

A total of 1925 patients with non-haemorrhagic moyamoya disease admitted between 1 April 2012 and 31 March 2014 in Japan.

MAIN OUTCOME MEASURE

We performed propensity score-matched analysis to examine the association between prehospital antiplatelet use and no significant disability on hospital admission, as defined by a modified Rankin Scale score of 0 or 1.

RESULTS

Propensity-matched patients who received prehospital antiplatelet drugs were associated with a good outcome on hospital admission (OR adjusted for all covariates, 3.82; 95% CI 1.22 to 11.99) compared with those who did not receive antiplatelet drugs prior to hospital admission.

CONCLUSIONS

Prehospital antiplatelet use was significantly associated with good functional status on hospital admission among patients with non-haemorrhagic moyamoya disease in Japan. Our results suggest that prehospital antiplatelet use should be considered when evaluating outcomes of patients with non-haemorrhagic moyamoya disease.